中国玉米根系生物量及空间分布特征

发布时间：2018-04-08 22:32

  本文选题：碳固定　切入点：全球变暖　出处：《中国农业大学》2016年博士论文

【摘要】：理解农作物根系生物量(RB)、空间和垂直分布模式及其主要驱动因子,对于评估生态系统功能,以及解决保障粮食安全和缓解全球变暖的农业挑战有重要意义。玉米作为全球分布最广泛的作物,其庞大的根系系统,可以通过地下部输入,在土壤碳循环方面具有巨大作用。中国幅员辽阔,跨越众多气候带和土壤带,玉米种植遍布全国,使得中国玉米根系空间分布的研究在全球地下部生物地理学分布规律的探索中具有典型性和代表性。同时,中国全国尺度玉米根系数据信息对于发展生态系统模型、作物生长模型、气候模型等也发挥着重要作用,鉴于全球性众多生态系统,特别是农田生态系统,根系数据的缺乏。本研究收集整理来自于311篇文献和16个农田生态系统实验站的玉米根系数据,最终筛选获得共898个玉米根系剖面,其中257个剖面有大于4层的取样深度,年份跨越1986-2012年。采用描述性统计分析、地统计分析等方法,分析中国玉米RB及其空间分布特征。同时,采用偏最小二乘法(PLS)结合气候、土壤、地形、农田管理等环境因子,探索玉米根系分布模式的主要驱动因子。在此基础上,估算中国玉米根系生物量碳(RBC)输入量,预测玉米RB及根系深度(RD)空间分布情况。全文主要结论如下：(1)全国范围,单株玉米RB平均值为30.10 g plant-1 (8.20-88.90 g plant-1)或者每平方米0.18kgm-2 (0.05-0.38 kg m-2),不同玉米种植生态区RB分布模式不同。单株水平,北方春播玉米区RB最大,其余4个玉米种植生态区之间RB数值差异不显著；群体水平,不同玉米种植生态区RB差异更明显,北方春播玉米区RB显著高于其余4区,黄淮海夏播玉米区RB显著高于南方丘陵玉米区。反距离权重(1DW)插值得到北方春播玉米区、黄淮海夏播玉米区和西北内陆玉米区RB较大(密度图),西南山地丘陵玉米区和南方丘陵玉米区RB较小(密度图)。同时,北方春播玉米区和黄淮海夏播玉米区播种面积大,而西北内陆玉米区、西南山地丘陵玉米区和南方丘陵玉米区播种面积较小。因此,总RB空间分布呈现明显的从北像南、从东向西递减的趋势,以北方春播玉米区和黄淮海夏播玉米区总RB最大。在此基础上估算中国玉米根系RBC平均为0.08kgC m-2,结合全国总播种面积,加权相加获得共22.92 Tg C yr-1以干重的形式输入到土壤碳库。(2)全国范围,玉米外推D50(50%根系所在深度)均值为11.33 cm (3.45-25.18 cm),外推D95(95%根系所在深度)均值为94.34 cm (12.62-175.95 cm).不同玉米种植生态区外推D50差异显著,北方春播玉米区西北内陆玉米区黄淮海夏播玉米区西南山地丘陵玉米区。外推D95差异也显著,分布规律略有不同,黄淮海夏播玉米区北方春播玉米区西北内陆玉米区西南山地丘陵玉米区。总体上,0-80 cm土层内,北方春播玉米区根系剖面分布最深,黄淮海夏播玉米区和西北内陆玉米区根系剖面分布相似；然而,黄淮海夏播玉米区外推D95在各生态区中最深。此外,西南山地丘陵玉米区根系剖面分布最浅。反距离权重插值得到全国范围RD空间分布特征也存在由北向南降低的趋势,北方春播玉米区和黄淮海夏播玉米区整体根系剖面分布最深,西北内陆玉米区次之,西南山地丘陵玉米区根系最浅。根据Logistic dose-response curve (LDR)模型计算全国范围平均71.53%玉米根系分布在表层20 cm中,估算得到表层20 cm土层玉米RBC含量为16.39TgC。(3)包含气候、土壤、地形以及农田管理措施因子的PLS模型对全国范围RB和RD变异的解释量分别为42.40%和56.70%。本研究揭示了影响玉米RB及RD分布的不同驱动因子。在所有生物及非生物因素中,玉米RB与种植密度、籽粒产量、4月份降水量、年均降水量、5月份日照时数、土壤有机碳含量以及土壤砂粒含量成正比,与10月份降水、土壤pH、钾肥施用量以及7月份降水量成反比。然而,玉米RD与土壤砂粒含量、pH、年均日照时数、9月日照时数以及土壤阳离子交换量成正比,与坡度、海拔、土壤黏粒含量、土壤容重以及7月份日照时数成反比。农田管理措施(特别是种植密度)是玉米RB空间分布的主导因子,土壤发挥的作用较弱；然而,玉米RD对于土壤性质(特别是砂粒含量和pH)及地形因子更敏感。影响RB和RD的气候因子也不尽相同,RB受到降水量的强烈影响,而RD对日照时数的响应更明显。本研究认为PLS模型预测RB和RD空间分布模式与IDW插值结果相比更为可靠。(4)1986-2012年中国玉米RB没有发生显著改变。近十年间(2002-2012),单株水平RB没有显著变化,但是群体水平RB显著降低,而种植密度变化幅度不大。根系生物量下降的变化趋势显然与地上部籽粒产量升高的变化趋势相反。在两个玉米主产区,北方春播玉米区近十年单株水平和群体水平RB都呈现显著下降的趋势,与地上部籽粒产量增加的趋势相反。同时,外推D50和外推D95都显著增加。黄淮海夏播玉米区RB变化不显著,20022009年RB变化趋势与籽粒产量相同,而2009-2012年RB变化趋势与籽粒产量完全相反。引起思考的是,外推D95随时间的变化趋势与地上部籽粒产量的变化趋势完全一致,表明近十年中国玉米产量增加很可能与根系深度增加有着密切的关联。
[Abstract]:Crop root biomass (RB), and to understand the spatial vertical distribution pattern and its main driving factors for the evaluation of ecosystem function, and solve the food security and alleviate global warming challenges of agriculture has important significance. As the world's most widely distributed corn crop, its large root system, through the underground input, great role in soil carbon cycle. Chinese vast, across a wide range of climatic zones and soil with corn planting, all over the country, the distribution of maize root Chinese space is typical and representative in the exploration of global underground biogeography distribution. At the same time, the national scale Chinese maize root data information for the development of ecological system model, crop growth model, climate models also play an important role, many because of the global ecosystem, especially the farmland ecological system, Lack of root data. This study collected data from maize root experiment station in 311 documents and 16 of farmland ecosystem were obtained a total of 898 maize root profile, 257 of which have more than 4 layer sampling depth profile, the year spans 1986-2012 years. By analysis of descriptive statistics, statistical analysis methods of analysis Chinese maize RB and its spatial distribution characteristics. At the same time, by using partial least squares (PLS) combined with the climate, soil, topography, soil management and other environmental factors, explore the main driving factors of maize root distribution patterns. On this basis, estimates of root biomass carbon (RBC) Chinese input, RB forecast Maize root and depth (RD) spatial distribution. The main conclusions are as follows: (1) the scope of corn plant with an average RB of 30.10 g plant-1 (8.20-88.90 g plant-1) or 0.18kgm-2 per square meter (0.05-0.38 kg m -2), different maize planting ecological distribution of RB in different modes. Individual level, the northern spring maize region RB, the remaining 4 corn RB showed no significant difference between the numerical ecological zone; population level, different maize planting ecological zone RB more obvious differences, the northern spring maize region of RB was significantly higher than the other 4 areas, in summer sowing corn RB was significantly higher than that of Maize in hilly area. The inverse distance weighted (1DW) interpolation to get the northern spring maize region, Huanghuaihai Summer Maize Region and northwest inland region RB (corn density map), the larger southwest Maize Zone in Hilly and southern hilly region RB (small corn density map). At the same time, the northern spring maize and Huanghuaihai summer maize planting area of large area, and the Inland Northwest corn area, hilly area and southwest maize sowing maize in hilly area is smaller. Therefore, the distribution of total RB space obviously like South from the north, from east to West A decreasing trend, with the northern spring maize region and Huanghuaihai summer sowing maize total RB area. Based on the estimation of Chinese maize root RBC averaged 0.08kgC m-2, combined with the weighted sum of the total sown area, obtained a total of 22.92 Tg C yr-1 on a dry weight in the form of input to the soil carbon pool. (2) the scope of corn D50 extrapolation (50% roots depth) mean of 11.33 cm (3.45-25.18 cm), D95 (95% roots depth extrapolation) mean of 94.34 cm (12.62-175.95 cm). Different corn planting ecological zone extrapolation D50 significantly, corn area of southwest hilly area of maize Huanghuaihai summer maize area in Northwest inland region in North. Extrapolation D95 significantly, distribution is slightly different, the northern spring maize area area of northwest inland region in southwest hilly area of Maize in maize Huanghuaihai summer. In total, 0-80 cm soil layer, the northern spring maize area root profile The cloth is the deepest, Huanghuaihai Summer Maize Region and northwest region of maize root profile distribution is similar; however, Huanghuaihai Summer Maize Region in different ecological regions in the D95 extrapolation most. In addition, the southwest hilly area of maize root profile distribution of the shallow. Inverse distance weighted interpolation to get the nationwide distribution of RD space are reduced by North South trend, northern spring maize region and Huanghuaihai summer sowing maize root zone overall profile most inland Northwest corn region, southwest Maize Zone in mountainous and hilly areas of the shallow root. According to the Logistic dose-response curve (LDR) to calculate the average nationwide 71.53% maize root distribution on the surface of 20 cm in the model, the estimated surface 20 cm layer of maize RBC was 16.39TgC. (3) including climate, soil, topography and soil management measure factor PLS model of national RB and RD variation accounted for 42.40% and respectively. 56.70%. this study reveals the impact of maize RB and RD distribution in different driving factors. In all the biological and non biological factors in Maize RB and planting density, grain yield, April precipitation, annual precipitation, sunshine hours in May, the content of soil organic carbon and soil sand content is proportional to, and October precipitation, soil pH, dosage and potassium is inversely proportional to the precipitation in July. However, the maize RD and soil sand content, pH, the average annual sunshine hours, September sunshine hours and the soil cation exchange capacity is proportional to the slope, elevation, soil clay content, soil bulk density and sunshine hours in July is inversely proportional to the farmland management measures (especially the planting density) is the dominant factor of maize RB spatial distribution, weak soil play; however, RD for corn soil properties (especially the sand content and pH) and the terrain factor is more sensitive. The effects of RB and RD for the climate Children are not the same, RB is strongly influenced by precipitation, and RD on the sunshine duration response is more obvious. This study shows that the PLS model for predicting RB and RD spatial distribution pattern and IDW interpolation results compared to more reliable. (4) 1986-2012 years China corn RB did not change significantly. The last ten years (2002-2012), individual level of RB did not change significantly, but the level of RB group was significantly decreased, while the planting density has little change. The changing trends of root biomass decreased obviously with the increase in grain yield. In two maize producing areas, the northern spring maize region in recent ten years, individual level and group level RB all showed a significant downward trend, in contrast with the trend of upper grain yield increased. At the same time, D50 and D95 are extrapolated extrapolation increased significantly. In Huanghuaihai Summer Maize Region of RB did not change significantly, 20022009 years RB and grain yield the same trend, 2009-2012 years the change trend of RB and the grain yield is completely opposite. Thinking caused, trend extrapolation D95 trends over time and the grain yield is completely consistent, shows that with the increase of China maize yield nearly ten years and is likely to increase the root depth are closely related.

【学位授予单位】：中国农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S513
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本文编号：1723668